Trechus shangensis, Belousov & Kabak, 2020

Belousov, Igor A. & Kabak, Ilya I., 2020, New Trechus species of the kozlovi group from Sichuan (Coleoptera: Carabidae), Zootaxa 4786 (4), pp. 451-484 : 465-467

Trechus shangensis sp. n.

( Fig. 15, 18 )

urn:lsid:zoobank.org:act:1AE7B28D-4380-457B-B9A8-5B44659BFC1B

Type material: Holotype: 1(1) ♂, “ China, NW Sichuan, NW of Lixian , 10 km WSW of Shangmeng, alp. scree 3850–4000m, 25.07.2002, Belousov I. & Kabak I. leg.” [31º39´40´´N / 103º01´50´´ E] ( ZISP) . Paratypes: 43(8) ♂♂,

25♀♀, collected with holotype ( IZAS, BMNH, SMNS, ZISP, ZSM, CAG, CBK, CDW, CJS, CVZ) ; 34(12) ♂♂, 27♀♀, “ China, NW Sichuan, NW of Lixian , 12 km WSW of Shangmeng, alp., scree 4000–4500 m, 26.07.2002, Belousov I. & Kabak I. leg.” [31º39´00´´N / 103º01´10´´ E] ( MPU, CBK, CAK) ; 8(7) ♂♂, 15♀♀, “ China, NW Sichuan, NW of Lixian , 9 km W of Shangmeng, scree above timber-line, 3700–3800 m, 23.07.2002, Belousov I. & Kabak I. leg.” [31º40´30´´N / 103º02´25´´ E] ( ZISP, ZSM, CBK) .

Description. Body elongate-oval, moderately constricted at pronotal base, convex ( Fig. 15). Appendages moderately long and rather thick. Upperside pitchy black to reddish brown, often disc of pronotum, suture and margins of elytra paler, tinged with reddish. Anterior portion of head before clypeal suture amber brownish. Legs uniformly pale reddish.Antennae either uniformly pale reddish brown or vaguely obscured in middle and distal portions beginning from apical parts of segments 3–5.

Head of medium size, eyes average and subconvex, tempora rather long and slightly convex, with a few very short hairs. Frontal furrows evenly impressed, subangulate or arcuate, markedly approaching in middle, deepest just behind their mid-length. Supraorbital setae located in lines subparallel to body axis, posterior seta far behind posterior margin of eye. Pores of both anterior and posterior setae foveolate, though posterior one shallower.

Pronotum convex, subcordate, moderately constricted at base, with maximum width in apical third. Its sides broadly arcuate in anterior part, moderately sinuate before hind angles, the latter large, subrectangular or acute, occasionally produced outwards. Posterior margin straight, oblique at sides; anterior margin straight. Anterior angles marked though rounded. Lateral margins moderately reflexed, lateral groove narrow to average, slightly widened posteriorly. Prebasal transverse impression parallel to basal margin, markedly curved near basal foveae, not sharply engraved. Basal foveae large and deep. Apical transverse impression distinct laterally, shallow medially. Anterior marginal seta located in anterior third of pronotum, posterior seta at hind angle. Base of pronotum slightly to markedly longitudinally rugose. Median line well impressed, deepest near its base, not reaching anterior margin of pronotum.

Elytra oblong-oval, with sides evenly and broadly arcuate, widest slightly behind their mid-length. Humeri marked, but broadly rounded. Elytra conjointly rounded apically, each with a distinct subapical sinuation. Striation of elytra rather complete: striae 1–4 well impressed and entire, others shallow and shortened, becoming less distinguishable toward sides. All elytral striae slightly but distinctly punctured. Stria 2 surpassing level of preapical pore posteriad and usually reaching apical border of elytron, normally without distinct connection with stria 3; the latter joining stria 4 approximately at level of anterior end of apical striole; striae 5 and 6 joining each other far before elytral apex, near level of median group of umbilicate series; stria 7 joining apical striole and forming here a distinct sinuation. Parascutellar striole long and well engraved, parascutellar pore present. Apical recurrent striole deep, straight or slightly curved, rather long, though not reaching level of umbilicate pore 7, markedly divergent from suture anteriad, externally bordered by a well-developed carina. Apical triangle (consisting of three pores on apical slope) very long, angulo-apical pore located closer to exterior pore than to elytral suture. Lateral margins moderately reflexed, lateral groove of medium width.

Microsculpture well developed over entire body surface, consisting of isodiametric meshes on head, irregular and slightly transverse meshes on disc of pronotum, becoming coarser and less transverse toward base, and distinctly transverse meshes, partially transverse lines on elytra, latter with faint iridescent luster.

Fore tibiae flattened or shallowly grooved on exterior surface in middle part, occasionally with a few short and sparse hairs on anterior surface near inner apex of tibia. In male, two proximal segments of protarsi markedly dilated and inwards dentate.

Median lobe of aedeagus large, subcylindrical, rather thick, angularly bent at basal portion ( Fig. 18a ) in lateral view. Both ventral and dorsal margins distinctly emarginate before apex, the latter in shape of oblique disc. In dorsal view ( Fig. 18b ), median lobe rather wide, slightly dilated in apical third, gradually narrowing apically. Preputial field variable, always surpassing mid-length of median lobe. Ventral surface with a slight median carina. Apical lamella distinct, rather short, with convergent sides and broadly rounded apex in dorsal view. Sagittal lobe well developed, thickened but not grooved along its exterior surface. Parameres long and slender, straight in distal half, left paramere clearly longer, with a well-developed ventral apophysis; each paramere bearing 4 apical setae. Endophallus armature consisting of two slightly sclerotized pieces: proximal one semi-ring shaped, located near mid-length of median lobe close to its left wall, its dorsal part always with emargination of different shape and falcate lobe (see from above, Fig. 18b ); distal piece smaller, located largely in horizontal plane, overlapped by small scaly patch if viewed from left side and from above.

Sexual dimorphism. Males differ in smaller head (EW/HW, on average, 1.97 vs. 1.92 in females, p≤0.001; PW/HW, on average, 1.28 vs. 1.26 in females, p≤0.05).

Comparative notes. Doubtless, T. shangensis sp. n. belongs to the T. kozlovi species group, as confirmed by both the external morphology and the structure of the male genitalia. Within this speciose group, the new species is easily recognized by the shape of the median lobe, which is large and rather thick, sharply curved at basal third and with a well-developed apical disc ( Fig. 18 ). It is most similar to the sympatric T. mengensis sp. n. Their differences are discussed below.

Distribution. T. shangensis sp. n. is only known from the upper valley of a small river located WSW of the village of Shangmeng, NW of Lixian City, Lixian County, Sichuan.

Bionomics. The species occurs in a wide range of altitudes from 3700 to 4500 m, in the alpine and upper forest zones. It was collected from under stones in humicolous habitats and by sifting from the Rhododendron litter.

Derivatio nominis. The species epithet refers to the first part of the toponym “Shangmengxiang”, a village located near mountains where this species was found.

Figures

FIGURES 18–20. Male genitalia of Trechus spp. n., paratypes: a—lateral view, b—dorsal view. 18—T. shangensis sp. n.; 19—T. mengensis sp. n.; 20—T. cuspis sp. n.